As a size of a metal-oxide-silicon field effect transistor continuously decreases, especially after a feature size of a device reaches a nanowire scale, negative impact such as a short channel effect of the device is increasingly significant. Because of a limitation imposed by a thermoelectric potential KT/q theory, a subthreshold slope of a conventional MOSFET device cannot synchronously decrease as a size of the device decreases, and a subthreshold leakage current of the conventional MOSFET device continuously increases as a threshold voltage decreases. To overcome increasing challenges of the MOSFET at a nanometer size, a new device structure and a process and a manufacturing method of the new device structure have become a focus of a small-size device.
As a new device structure, a tunnel field-effect transistor (TFET) uses a band-to-band tunneling conduction mechanism, and is an extremely potential low power-consuming device applicable to system integration application and development. When specifically operating, a conventional point-to-point tunneling TFET is a gate-controlled P-I-N structure. That is, bands of a source region and a channel bend under an action of a gate voltage, and there is a band overlapping region. As the gate voltage increases, carriers in the band of the source region tunnel to the band of the channel, form a tunneling current (that is, an on-state current), and flow to a drain end under an action of an electric field. This conduction mechanism breaks through the limitation of the thermoelectric potential KT/q in a theoretical limit of the subthreshold slope of the conventional MOSFET, and theoretically, can implement a super-steep subthreshold slope less than 60 mV/dec at room temperature, so as to reduce a static leakage current of the device and further reduce static power consumption of the device.
However, currently, a subthreshold swing (SS, also referred to as a subthreshold slope) value of an actually used tunnel field-effect transistor still cannot be less than 60 mV/dec, and power consumption is relatively high.